1. Field of the Invention
The present invention relates to a semiconductor optical element, a semiconductor laser element, and method for manufacturing a semiconductor optical element and a semiconductor laser element, and method for manufacturing a semiconductor laser module and a semiconductor element.
2. Description of the Related Art
An essential part of semiconductor element designing is in the use of a plurality of semiconductors having different physical properties in different regions of a semiconductor element to achieve a semiconductor element with functions suitable for an intended use. Physical properties such as the band gap or the refractive index of the semiconductor are important factors that determine an element design. A semiconductor can be designed to have desired physical properties by changing the semiconductor materials to be deposited, and the type, the concentration, and a combination of doping impurities.
One way to change the physical properties of a semiconductor is disordering of crystal. Exemplary techniques for disordering of crystal include impurity free vacancy disordering (IFVD), in which semiconductor disordered crystals are obtained by atomic vacancy diffusion, and impurity diffusion, in which semiconductor disordered crystals are obtained by diffusion of impurities. These techniques are used in semiconductor laser elements, for example. When the optical power of a laser element is increased, however, the output facet may absorb the laser light and become heated. When the facet becomes heated, a phenomenon known as catastrophic optical damage (COD) might occur, and the reliability might become degraded. COD is a phenomenon in which the heat causes the facet to melt down, thereby causing an interruption in the functions of the laser element. To avoid COD, a technology making the facet transparent by disordering crystals is disclosed. Use of such a technology can raise the optical power limit at which COD occurs.
This technology of making the facet transparent by disordering crystals is aimed to reduce the laser light absorbed at the facet of the semiconductor element by increasing the band gap energy of a semiconductor region near the facet by semiconductor disordered crystals, thereby making the region near the facet transparent to the emission wavelength (see Japanese Patent Application Laid-open Nos. 2007-242718, H09-23037, H10-200190, 2001-15859, 2011-10349, for example). This transparent region is referred to as a window region. The area that is not transparent is referred to as a non-window region.
Also disclosed is a technology for manufacturing a semiconductor optical element having various functions by making the degrees of disordering of crystals different among a plurality of regions extending in the deposition direction of the semiconductor layers (see Japanese Patent Application Laid-open No. H06-77596, for example).